I picked these up to use with the playtex nurser bottles because of the price, about $6 for 100 liners. seeing as I was going through about 8 liners a day feeding my infant, i thought it was a great deal. You really get what you pay for. These are terrible. It was difficult to separate the liner from itself, hard to pull over the bottle, couldn't rip off the tabs you're suppose to rip off after pulling it over the bottle and worse of all they leaked!! It sucks that formula is so expensive and watching it leak out of the bottle as your baby is drinking is bad but its not as heartbreaking as when you give it another chance and you watch the pumped breast milk start to leak.